Question: Charlotte is running at a rate of $9\,\dfrac{\text{km}}{\text{h}}$. What is Charlotte's speed in $\dfrac{\text{m}}{\text{s}}$ ?
We will convert $9\,\dfrac{\text{km}}{\text{h}}$ to a rate in $\dfrac{\text{m}}{\text{s}}$ using the following conversion rates: There are $1000\text{ m}$ per $1\text{ km}$. There is $1\text{ h}$ per $3600\text{ s}$. $\begin{aligned} &\phantom{=}\dfrac{9\text{ km}}{1\text{ h}}\cdot\dfrac{1000\text{ m}}{1\text{ km}}\cdot\dfrac{1\text{ h}}{3600\text{ s}} \\\\ &=\dfrac{9\cdot1000\cdot1\cdot\cancel{\text{km}}\cdot\text{m}\cdot\cancel{\text{h}}}{1\cdot1\cdot3600\cdot\cancel{\text{h}}\cdot\cancel{\text{km}}\cdot\text{s}} \\\\ &=\dfrac{9000}{3600}\,\dfrac{\text{m}}{\text{s}} \\\\ &=\dfrac{5}{2}\,\dfrac{\text{m}}{\text{s}} \end{aligned}$ In conclusion, Charlotte's speed in $\dfrac{\text{m}}{\text{s}}$ is: $\dfrac{5}{2}\,\dfrac{\text{m}}{\text{s}}$